<div class="change">
  <h2>这是change组件</h2>
  <p> heroName: {{ heroName }} </p>
  <div class="sec">
    <button class="btn btn-primary" (click)="arms = '长剑'">改变武器</button>
    <app-change-child [arms]="arms"></app-change-child>
  </div>
</div>